Arlene Foster will take the reins in her first day as the sole unionist in Northern Ireland's faltering powersharing government.

She was named acting first minister after the mass resignation of her party colleagues amid a crisis sparked by a murder linked to members of the IRA.

Democratic Unionist leader Peter Robinson has asked the DUP finance minister to remain in the Executive to prevent Sinn Fein from taking over key ministerial posts.

The unionist walkout from the mandatory coalition came after the DUP failed to get the Assembly adjourned for a period to allow crisis talks to address the implications of the murder of Kevin McGuigan to take place.

The political furore over the killing intensified on Wednesday when three senior republicans were arrested in connection with the murder.

As he announced the resignations, Mr Robinson repeated a demand for the Government to suspend the institutions outright to enable space for the talks to happen. Northern Ireland Secretary Theresa Villiers last night rejected the call.

The fallout from the murder of Kevin McGuigan has already seen the Ulster Unionists resign their one ministerial post.

The exit of Mr Robinson along with three of the DUP's four other ministers, and its one junior minister, has left the 13 minister administration in freefall. The departments of health and social care; social development; enterprise trade and investment; and regional development are now effectively rudderless.

Collapse of power-sharing is not inevitable but its demise appears to have been hastened by a day of dramatic developments at Stormont on Thursday.

The DUP wanted all Assembly business suspended to allow crisis talks to take place about the political consequences of the murder of Mr McGuigan.

Mr Robinson's announcement came after Sinn Fein, the SDLP and the Ulster Unionists voted against a DUP proposal to adjourn the Assembly.

He issued a resignation ultimatum on Wednesday after the arrest of republicans Bobby Storey, Eddie Copeland and Brian Gillen over the fatal shooting of former IRA man Mr McGuigan. Mr Copeland and Mr Gillen remain in custody.

Police have said current members of the IRA were involved in last month's shooting of Mr McGuigan in a suspected revenge attack for the murder of former IRA commander Gerard "Jock" Davison in Belfast three months earlier.

The disclosures about the IRA have heaped pressure on Sinn Fein to explain why the supposedly defunct paramilitary organisation is still in existence.

Ms Foster said she has stayed on the Executive in order to deter actions by what she called "rogue" republican and nationalist ministers.

She told BBC's The View: "I have been placed there as a gatekeeper to make sure that Sinn Fein and the SDLP ministers don't take actions that will damage Northern Ireland and principally, let's be honest, that damage the unionist community.

"If anybody knows me and indeed knows the Democratic Unionist Party they know that I'm not going to put at risk to the people of Northern Ireland the possibility that rogue Sinn Fein or renegade SDLP ministers are going to take decisions that will harm the community in Northern Ireland."

But her remarks drew criticism from Sinn Fein's Gerry Kelly, who described them as "bigoted" and a "throwback" to the past.

He told the broadcaster: "To make this attack on nationalism - because it wasn't just republicanism, but on nationalism - and call ministers 'rogue ministers' is a complete nonsense."

Ms Villiers said re-instigating an independent authority to look at decommissioning command structures was one of the most "credible" options.

She told BBC Radio 4's Today programme: "I think that is certainly one of the most credible ideas. I think it wouldn't necessarily be appropriate to set up exactly the same structure that existed in the past and certainly one would need to ask it a different question. In the past the question was just about decommissioning and ceasefires.

"I think now it is very clear we want to see these paramilitary organisations disband altogether. We also want to investigate the role of members of these organisations in relation to criminality."

The Northern Ireland Secretary said it was "inevitable" that power-sharing would come under "huge strain".

She said: "I certainly wish that the DUP had been able to find a different way to deal with this situation but I also accept that it had put a huge strain on working relationships as it would in any situation where a leading figure in your coalition partner is arrested in relation to a murder case.

"That poses very real difficulties and very real strains so I am afraid it's inevitable that that was going to have a very significant impact on power sharing."

Ms Villiers called on Labour's new leader, to be named on Saturday, to continue the "bipartisan approach" on Northern Ireland.

"I think it would be gravely destabilising if a Jeremy Corbyn led Labour party decided to depart from that," she added.